The present disclosure relates to cleaning equipment, and more specifically, to a cleaning apparatus for heat exchanging coils.
Heat exchanging coils such air conditioning/refrigeration coils, process fluid coolers, hydraulic fluid coolers, and similar mechanical structures require regular cleaning to maintain efficient heat transfer. Such heat exchangers generally comprise a tube containing a refrigerant surrounded by a plurality of thin metal plates or fins. A fan drives ambient air through the fins and around the tubes to draw heat from the refrigerant. The fins serve to increase the surface area of heat transfer and, therefore, are generally stacked close together (passageways may be less than 2.5 millimeters wide). While such configuration improves the heat exchanging capacity, efficiency declines as the fins clog with oils, dust, pollen, plant seeds, process by-products, and other contaminants present in the ambient air.
Conventional coil cleaning methods include the use of chemical cleaners, brushes, high pressure water delivered from pressure washers or backpack sprayers, and compressed air. Each has advantages and disadvantages. Brushes and chemical cleaners may effectively loosen contaminants, but are ineffective at removing them from the coil. Water and water-based chemical spraying systems may remove oils that have caked onto the coil, but due to surface tension or friction of water, high pressure is required to force the liquid fluid and contaminants through the narrow passageways of the coil. Additionally, the large volume of water required to clean the coil can damage other components of the system. High pressure air effectively carries contaminants such as dust and debris out of the coil, but may not have enough force to loosen and remove hardened buildup or remove the oils which, if left in place, attract additional contaminants.
Both high pressure water and compressed air systems generally require small nozzles or orifices to deliver a high pressure stream of fluid. The small nozzles limit the effective cleaning area, which increases the amount of time it takes to clean the coil and the amount of cleaning fluid required. Additionally, the pressure required to remove contaminants from the coil is sufficient to bend, fold, or damage the thin metal fins. When fins are bent such that they abut adjacent fins or reduce the space between adjacent fins, heat exchanging efficiency is lost and the narrower passageways become more difficult to clean. Operators must use care in spraying the coil to avoid such damage.
In addition to conventional coil cleaning systems, the prior art discloses a low-pressure air coil cleaning system (U.S. Pat. No. 7,132,017), such as a leaf blower, that may be equipped with a cleaning fluid injector to create a “cleaning fluid mist.” The air pressure of the prior art system is too low to damage coil fins, but also too low to drive a cleaning fluid into the narrow coil passageways and force the cleaning fluid and contaminants out of the coil.
There is a need for an improved coil cleaning system that is capable of removing all types of contaminants from the narrow coil passageways in a single application, while also reducing the risk of damaging the coil fins and reducing the labor time needed.